I don't know what IH's market share for combines was during that time period (66-67), but it couldn't have been very large. Many IH farms (including our farm) had gone to MF or Gleaner, both of which both had strong dealerships in my area.

It took the 8-915 series for IH to "bottom out" on market share.

When the Axial Flow combines were finally released in 1977, IH had a huge resurgence and gained back a lot of old IH customers (including us). This resurgence came at the expense of MF and Gleaner.